965
FXUS10 KWNH 141649
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1245 PM EDT THU MAY 14 2020
VALID MAY 14/1200 UTC THRU MAY 18/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z NAM/GFS EVALUATION INCLUDING PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...CLOSED LOW OVER THE NORTHERN PLAINS AND UPPER GREAT LAKES
TODAY/TONIGHT...CROSSING NORTHERN NEW ENGLAND FRI...
...SURFACE LOW MOVING FROM THE NORTHERN PLAINS TONIGHT INTO
NORTHERN NEW ENGLAND FRI...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-12Z NAM BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE 12Z NAM/GFS ARE CLOSE TO THE CONSENSUS WITH THE SHORT WAVE
ENERGY TRACKING FROM THE INTERNATIONAL BORDER OF ND ACROSS THE
UPPER GREAT LAKES TODAY INTO EARLY TONIGHT. AFTER THAT TIME, THE
12Z NAM BECOMES FASTER AND DEEPER WITH THE SHORT WAVE CROSSING ME
AND NOVA SCOTIA FRI. IN RESPONSE TO THE SHORT WAVE, THE 12Z NAM
ALSO APPEARS TO BE TOO DEEP/TOO FAR NORTH WITH THE SURFACE LOW
CROSSING NORTHERN NEW ENGLAND FRI. THE 12Z GFS IS CLOSER TO THE
CONSENSUS THROUGHOUT THE PERIOD WITH THE SHORT WAVE, BUT MAY BE A
TAD SLOW WITH THE SURFACE LOW CROSSING ME (AS IT HAS BEEN FOR THE
PAST FEW MODEL CYCLES).
AT THIS POINT, WITH FAIRLY GOOD CLUSTERING (OUTSIDE OF THE NAM), A
NON-12Z NAM WAS THE PREFERRED BLENDED WITH INCREASING FORECAST
CONFIDENCE.
...CLOSED MID LEVEL LOW OFF THE PACIFIC NORTHWEST TODAY
MOVING
TO THE NORTHERN PLAINS SAT AND
THE UPPER GREAT LAKES SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM/00Z ECMWF BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
THE 12Z NAM/GFS ARE CLOSE TO THE CONSENSUS TAKING THE CLOSED MID
LEVEL LOW FROM JUST OFF THE PACIFIC NORTHWEST COAST THIS AFTERNOON
ACROSS THE NORTHERN PLAINS SAT. AFTER THAT TIME, THE 12Z GFS SLOWS
WITH THE MID LEVEL SYSTEM, AND DROPS IT SOUTHWEST OF THE CONSENSUS
(IN A POSITION NEARLY IDENTICAL TO THE 00Z CMC) BY 18/00Z. AS A
RESULT OF THE MID LEVEL SYSTEM SLOWING, THE 12Z GFS LOOKS A BIT
SLOW WITH THE SURFACE LOW POSITION BY THAT TIME.
IN CONTRAST, THE 12Z NAM REMAINS CLOSE TO THE LOOSE CONSENSUS
(WHICH INCLUDES THE 00Z ECMWF/00Z ECMWF MEAN/00Z GEFS MEAN) TAKING
THE CLOSED MID LEVEL LOW OVER WI/MI BY THE END OF THE PERIOD.
WHILE THE 00Z ECMWF IS CLOSE TO THE CONSENSUS WITH THE MID LEVEL
SYSTEM, IT MAY BE TOO FAR WITH THE SURFACE LOW AND ASSOCIATED
FRONT, WITH MUCH OF THE REST OF THE GUIDANCE SUGGESTING A SURFACE
LOW/FRONT FURTHER SOUTH. AT THIS POINT, THE PREFERRED BLEND IS THE
12Z NAM/00Z ECMWF (WITH ENSEMBLE SUPPORT), THOUGH THE 12Z GFS
SOLUTION IS NOT UNUSABLE, ESPECIALLY WITH THE SURFACE SYSTEMS. DUE
TO THE SPREAD NOT ONLY AT THE SURFACE BUT IN THE MID LEVELS,
FORECAST CONFIDENCE IS SLIGHTLY BELOW AVERAGE.
...DEVELOPING LONG WAVE TROUGH MOVING FROM NORTHERN MEXICO INTO
CENTRAL TX SAT...THEN INTO
THE LOWER MS VALLEY SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/00Z ECMWF/00Z CMC BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
BOTH THE 12Z NAM/GFS ARE CLOSE TO THE CONSENSUS TAKING A
DEVELOPING LONG WAVE TROUGH OUT OF NORTHERN MEXICO TONIGHT AND FRI
INTO CENTRAL TX SAT. FROM THIS POINT, THE 12Z NAM SLOWS WITH A
CLOSING MID LEVEL LOW HANGING BACK OVER EAST TX SUN (WHICH IS VERY
CLOSE TO THE 00Z UKMET POSITION). THE 12Z GFS IS CLOSER TO THE
REMAINDER OF THE GUIDANCE TAKING THE LONG WAVE TROUGH ACROSS THE
LOWER MS VALLEY LATE SAT INTO SUN. WITH NO OBVIOUS MECHANISM FOR
CLOSING THE MID LEVEL SYSTEM OFF OVER EAST TX, AT THIS POINT THE
12Z NAM/00Z UKMET LOOK TOO SLOW WITH THEIR DEPICTION OF THE MID
LEVEL SYSTEM. HOWEVER, THESE SOLUTIONS CANNOT BE TOTALLY
ELIMINATED, AS THERE HAS BEEN AN OVERALL MODEL TENDENCY TO SLOW
WITH THE LONG WAVE TROUGH.
OVERALL, A 12Z GFS/00Z ECMWF/00Z CMC BLEND IS PREFERRED WITH THIS
SYSTEM. GIVEN THE SPREAD STILL IN PLACE WITH THIS SYSTEM (AS WELL
AS THE OVERALL TREND OF SLOWING THE LONG WAVE TROUGH), FORECAST
CONFIDENCE IS SLIGHTLY BELOW AVERAGE.
..LOW PRESSURE DEVELOPING NEAR THE BAHAMAS FRI NIGHT INTO SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/00Z ECMWF/00Z ECMWF MEAN BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE 12Z NAM/GFS ARE CLOSE WITH THE DEVELOPING SURFACE LOW AS IT
TRACKS FROM SOUTHEAST FL FRI/FRI NIGHT TO A POSITION NORTH OF THE
BAHAMAS BY 18/00Z. BY THAT TIME, THE 12Z NAM BIT FURTHER EAST THAT
THE 12Z GFS/00Z ECMWF/00Z ECMWF ENSEMBLE MEAN, WHILE THE 00Z CMC
IS A BIT WEST OF THAT POSITION. ONLY THE 00Z UKMET SEEMS TO BE TOO
FAR FROM THE CONSENSUS, TAKING THIS SYSTEM MUCH FURTHER EAST (AS
HAS BEEN ITS TREND THE PAST THREE CYCLES).
HOWEVER, BASED ON CONSISTENCY OF THE GFS/ECMWF/ECMWF ENSEMBLE MEAN
OVER THE PAST THREE MODEL CYCLES, THE 12Z GFS/00Z ECMWF/00Z ECMWF
MEAN COMPRISE THE PREFERRED BLEND. WITH ONLY THE 12Z UKMET
STRAYING FROM THE TIGHTENING MODEL CLUSTER WITH THIS SYSTEM,
FORECAST CONFIDENCE IS SLIGHTLY ABOVE AVERAGE.
...LARGE CLOSED MID LEVEL LOW DRIFTING TOWARD THE PACIFIC
NORTHWEST SAT/SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THERE IS GENERALLY GOOD MODEL AGREEMENT TAKING A CLOSED MID LEVEL
LOW FROM 48N 161W THIS AFTERNOON AND TRACKING IT TO A POSITION OF
THE SOUTHERN
OR/NORTHERN CA COAST BY 18/00Z. GIVEN THE IMPRESSIVE MODEL
CLUSTERING, A GENERAL MODEL BLEND IS PREFERRED WITH ABOVE AVERAGE
FORECAST CONFIDENCE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
HAYES
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